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STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Faculty of Civil EngineeringDr.ing. Nagy‐György T.
Dr. NAGY‐GYÖRGY TamásProfessor
E‐mail: tamas.nagy‐gyorgy@upt.ro
Tel:+40 256 403 935
Web:http://www.ct.upt.ro/users/TamasNagyGyorgy/index.htm
Office:A219
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 2
1. Strengthening for flexure using EB‐FRP
2. RC beam strengthened for flexure ‐ Application
3. Shear strengthening using EB‐FRP
4. RC beam strengthened for shear ‐ Application
5. Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 3
Strengthening for flexure using EB‐FRP
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Initial situation
Initial load Mo = service moment acting duringstrengthening
Mo is typically larger than the cracking moment Mcr
the calculation is based on a cracked section
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 4
Strengthening for flexure using EB‐FRP
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Constitutive material models
(Stijn Matthys, Ghent University)
For FRPServiceability Limit State (SLS)
‐ reversible, long term effect
Ultimate Limit State (ULS)1.35 1.5 1.5 , ,
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 5
Strengthening for flexure using EB‐FRP Failure modes – ULS
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Failure modes – Ultimate Limit States
1. Full composite action of concrete and FRP is maintaineduntil the concrete reaches crushing in compression or theFRP fails in tension (such failure modes may also be characterizedas “ideal”)
2. Composite action is lost prior to class 1 failure, e.g. dueto peeling‐off or by debonding of the FRP
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 6
Strengthening for flexure using EB‐FRP
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Failure modes – Full composite action
Steel yielding followed by concrete crushing
Steel yielding followed by FRP fracture
Concrete crushing or FRP failure without steel yielding
Rupture of steel, before concrete crushing or FRP failure
Failure modes – ULS
Allowed
To be avoided
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 7
Strengthening for flexure using EB‐FRP
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Failure modes – Loss of composite action
• Debonding and bond failure modes
Failure modes – ULS
fib
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 8
Strengthening for flexure using EB‐FRP
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Failure modes – Loss of composite action
Failure modes – ULS
fib
Bond behaviour of RC members strengthened with FRPMost failures observed caused by peeling‐off of the EBR element. These depends on the starting point:
in an uncracked anchorage zone
caused at flexural cracks
caused at shear cracks
caused by the unevenness of the concrete surface fib
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 9
Strengthening for flexure using EB‐FRP
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Failure modes – Loss of composite action
Failure modes – ULS
Bond behaviour of RC members strengthened with FRPAlso was observed FRP end shear failure (or concrete rip‐off)
fib
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 10
1. Strengthening for flexure using EB‐FRP
2. RC beam strengthened for flexure ‐ Application
3. Shear strengthening using EB‐FRP
4. RC beam strengthened for shear ‐ Application
5. Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 11
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
RC beam strengthened with CFRP composite for bending
1. SYSTEM
L = 4.1 m
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 12
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
2. CROSS SECTION AND MATERIALS
RC beam (indoor)h = 40 cmb = 20 cmd = 36.7 cmAs1 = 2φ16 = 4.02 cm2
Concrete:C30/37fck = 30 N/mm2
Ec = 33000 N/mm2
fctm = 2.9 N/mm2
Steel:fyk = 500 N/mm2
Es = 200000 N/mm2
20
40
CFRP compositebf = 80 mmtf = 1.2 mmEfk = 165000 N/mm2
εfk = 17 ‰
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 13
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
1. Self‐weight G = _____ kN/m
2. Live load before strengthening q1 = 8.0 kN/m
3. Additional live load q2 = 18.0 kN/m
4. Live load after strengthening q1 + q2 = 26.0 kN/m
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 14
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
Fundamental load combination 1.35∑ , 1.5 ,
Total load before strengthening _______ /
Bending moment before strengthening _____kNm
Total design load _______ /
Total bending moment _______kNm
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 15
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
____
1.5
_____
1.15
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 16
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
Resisting moment of the unstrengthened member
Where 1 0,5
and
_____ ______ 0.8 1 0.4 _____
/_______
_______
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 17
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. INITIAL SITUATION
Service moment self‐weight + q1
Calculation of the neutral axis depth :
______
12 1
Where ‐ coefficient of equivalence
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 18
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. INITIAL SITUATION
0.5 0
0.5 · ______ · _____ · ______ · ______ 0
→ ____, __
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 19
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. INITIAL SITUATION
The concrete strain at the top fibre can be expressed as:
0, _________
Where
3 1
________________
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 20
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. INITIAL SITUATION
Based on the strain compatibility, the strain at the extreme tension fiber can be derived as
0. __________
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 21
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
General condition
It is assumed that flexural failure takes place when one of thefollowing conditions is met:
‐ The maximum concrete compressive strain ( ) is reached.
‐ The maximum FRP tensile strain ( ) is reached.
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 22
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
∑ 0 → 0.85
Where
0.8
0.4
Additional safety factor
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 23
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
∑ 0 → 0.85 only iterative solving is possible
1st proposal 102
_______
0.85 dif? %_______ _______
2nd proposal _______
______________ _______ dif ? %
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 24
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
3rd proposal
_______
______________ ______________[N]
difference _______%
_______
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 25
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
It must be verified if
,
(Stijn Matthys, Ghent University)
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 26
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
It must be verified if
,
Deformability condition
(Stijn Matthys, Ghent University)
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 27
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
It must be verified if
,
, 5.0 5.0 _______ _______‰
, _______‰ _______‰ _______
Deformability condition
(Stijn Matthys, Ghent University)
in ‰ !!!
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 28
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
It must be verified if
, FRP bond failure
min ;
0.7517‰1.1
In conformity of CNR‐DT 200/2004
______‰
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 29
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
It must be verified if
, FRP bond failure
min ;
1·
2 · Γ·
3.0 ‐ coefficient
Γ 0.03 · · ‐ the specific fracture energy of the FRP ‐ concrete interface
2 ⁄1 400⁄ 1
is a geometric coefficient depending on both width of thestrengthened beam and width of the FRP system. If /0.33, the value for corresponding to / 0.33 is adopted.
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 30
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
It must be verified if
,
min ; ________
1·
2 · Γ· ________
3.0
Γ 0.03 · · ______ ⁄ ______
2
1 400
______
If / 0.33, the value for corresponding to / 0.33 is adopted
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 31
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
Verification of the strain in reinforcement
0. ________ 0. ______
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 32
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
The flexural capacity of the strengthened member:
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 33
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
5. ANALYSIS IN ULS
The flexural capacity of the strengthened member:
1
_______ ________
_________
______ ______
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 34
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING FOR ANCHORAGE FAILURE
(Stijn Matthys, Ghent University)
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 35
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING FOR ANCHORAGE FAILURE
ANCHORAGE FAILURE MODES
Type 1: at interface
Type 2: at internal steel reinforcement level
(Stijn Matthys, Ghent University)
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 36
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING FOR ANCHORAGE FAILURE
lb
Af
As1
Nb
Ns1
Nf
z
Capacity of the unstrengthenedsection
Capacity of the strengthened section
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 37
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING FOR ANCHORAGE FAILURE
The maximum FRP force which can be anchored:
, 2
1.0 0.9 influence of inclined cracks on bond strength1.0 influence of the concrete faces with low compaction
⁄⁄ 1 geometric coefficient, in function of ⁄
0.205 for CFRP laminate
The optimal bond length:
2 ·
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 38
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING FOR ANCHORAGE FAILURE ‐ DEBONDING
The maximum FRP force which can be anchored:
, 2 ______
The optimal bond length:
2 · _______
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 39
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING FOR ANCHORAGE FAILURE ‐ DEBONDING
0.9 330200190 185
720
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 40
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING FOR ANCHORAGE FAILURE ‐ DEBONDING
20 cm 18.5 cm
L=4.1 m
shifting
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 41
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING FOR ANCHORAGE FAILURE ‐ DEBONDING
CHECKING THE ANCHORAGE FORCE AT THE DISTANCE OF :
1. Computation of and
2. Computation of
from ∑ 0 → 0.85
by several iteration the values for , and will be obtained
3. Whith obtained, computation of the effective force in the composite and compare
,
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 42
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING ANCHORAGE FAILURE – CONCRETE RIP‐OFF(end shear failure)
a > L + d
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 43
RC beam strengthened for flexure
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
6. CHECKING ANCHORAGE FAILURE – CONCRETE RIP‐OFF
_______
where
0.15 · 3 1 100 design value of resisting shear strength of concrete
1
(end shear failure)
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 44
1. Strengthening for flexure using EB‐FRP
2. RC beam strengthened for flexure ‐ Application
3. Shear strengthening using EB‐FRP
4. RC beam strengthened for shear ‐ Application
5. Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 45
Shear strengthening
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
fib
SHEAR STRENGTHENING
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 46
Shear strengthening
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
(Barros Joaquim , University of Minho)
SHEAR STRENGTHENING
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 47
Shear strengthening
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
SHEAR CAPACITY OF THE STRENGTHENED MEMBERS
, , , ,
, concrete contribution to the shear capacity
, steel contribution to the shear capacity
, FRP contribution to the shear capacity
, the ultimate strength of the concretet strut
EC2 or ACI318
fibCNR‐DT200ACI4408
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 48
Shear strengthening
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
SHEAR CAPACITY OF THE STRENGTHENED MEMBERS
For RC member with rectangular cross‐section with U‐wrapped orcompletely wrapped configurations, the FRP contribution to the shearcapacity shall be calculated as:
fib ,
CNR ,
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 49
1. Strengthening for flexure using EB‐FRP
2. RC beam strengthened for flexure ‐ Application
3. Shear strengthening using EB‐FRP
4. RC beam strengthened for shear ‐ Application
5. Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 50
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
RC beam strengthened with CFRP composite for bending
1. SYSTEM
L = 4.1 m
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 51
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
2. CROSS SECTION AND MATERIALS
RC beam (indoor)h = 40 cmb = 20 cmd = 36.7 cmAs1 = 2φ16 = 4.02 cm2
φw = φ6 sw = 150 mm
Concrete:C30/37fck = 30 N/mm2
Ec = 33000 N/mm2
fctm = 2.9 N/mm2
CFRP compositewf = 200 mmsf = 200 mmtf = 0.131 mmEfk = 238000 N/mm2
εfk = 18 ‰
Steel:fywk = 500 N/mm2
Es = 200000 N/mm2
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 52
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
1. Self‐weight G = 2.0 kN/m
2. Live load before strengthening q1 = 8.0 kN/m
3. Additional live load q2 = 18.0 kN/m
4. Live load after strengthening q1 + q2 = 26.0 kN/m
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 53
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
1. Self‐weight G = 2.0 kN/m
2. Live load before strengthening q1 = 8.0 kN/m
3. Additional live load q2 = 18.0 kN/m
4. Live load after strengthening q1 + q2 = 26.0 kN/m
1.35 , 1.5 ,Fundamental load combination
→ · 2 _______kN
41.7 /
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 54
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
20
1.5
435
1.15
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 55
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
Resisting shear force of the unstrengthened member
min , , ,Where
, · · ·
, · · ·
0,6 1 250strength reduction factor for concrete cracked in shear
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 56
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
Resisting shear force of the unstrengthened member
min , , , _________Where
, · · ·
, _______
, · · ·
, _________
0,6 1 ____strength reduction factor for concrete cracked in shear
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 57
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
3. LOADS AND DESIGN VALUES
Shear force difference:
, ______
L = 4.1 m
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 58
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. FRP CONTRIBUTION TO THE SHEAR CAPACITY
,10.9 · 2 · ·
(formula for U‐wrapped configurations – CNR DT200)
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 59
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. FRP CONTRIBUTION TO THE SHEAR CAPACITY
,10.9 · 2 · ·
Where, for a U‐wrappwed configuration
113 ·
·min 0.9 ,
2 ·
1·
2 · · Γ
the optimal bond length
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 60
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. FRP CONTRIBUTION TO THE SHEAR CAPACITY
,10.9 · 2 · ·
Where, for a U‐wrapped configuration
1·
2 · · Γ
Γ 0.03 · · ‐ the specific fracture energy of the FRP ‐ concrete interface
2 ⁄1 400⁄ 1
When calculating , the coefficient shall be considered asfollows: for discrete FRP strips application, and ;for FRP systems installed continuously along the span length of themember it shall be permitted to considermin 0.9 , · sin /sin
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 61
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. FRP CONTRIBUTION TO THE SHEAR CAPACITY
,10.9 · 2 · ·
Where, for a U‐wrappwed configuration
1 for a continues fiber application
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 62
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. FRP CONTRIBUTION TO THE SHEAR CAPACITY
⁄⁄ _______
min 0.9 , ·sin
sin _______
Γ 0.03 · · _______
1·
2 · · Γ686.09
2 · ____
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 63
RC beam strengthened for shear
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Application
4. FRP CONTRIBUTION TO THE SHEAR CAPACITY
113 ·
·min 0.9 , _______
,10.9 · 2 · ·
, ________
, ,
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 64
1. Strengthening for flexure using EB‐FRP
2. RC beam strengthened for flexure ‐ Application
3. Shear strengthening using EB‐FRP
4. RC beam strengthened for shear ‐ Application
5. Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 65
Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
CONFINEMENT EFFECTS
(Τhanasis Triantafillou, University of Patras)
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 66
Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
CONFINEMENT EFFECTS
Comparison of the axial compressive stress as a function of the axial strain for an unreinforced,reinforced with steel stirrups and FRP‐wrapped column (Holloway and Head, 2001).
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 67
Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
CONFINEMENT EFFECTS higher strength
higher deformation
(fib)
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 68
Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
CONFINEMENT JACKETS SHOULD BE DESIGNED
To increase deformation capacity (chord rotation or ductility factor)
To increase shear resistance in such way, that flexural failure precedes shear failure.
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 69
Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
CONFINEMENT JACKETS SHOULDN'T BE USED TO INCREASE FLEXURAL RESISTANCE
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 70
Confinement
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
CONFINEMENT DESIGN
Circular column
fib
!f = fu
Rectangular column
!
Teng et. al.
Faculty of Civil EngineeringDr.ing. Nagy‐György T. 71
Dr. NAGY‐GYÖRGY TamásProfessor
E‐mail: tamas.nagy‐gyorgy@upt.roTel: +40 256 403 935Web: http://www.ct.upt.ro/users/TamasNagyGyorgy/index.htm Office: A219
STRENGTHENING OF STRUCTURES USING FRP TECHNIQUES
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